Sequence relay



April 1947- H. c. PRA TT SEQUENCE RELAY Filed Aug. 9, 194a 3 Sheets-Sheet l April 15, 1947. H. c. PRATT 2,419,032

SEQUENCE RELAY April 15, 1947. H.'C. PRATT SEQUENCE RELAY Filed Aug. 9, 1943 5 Sheets-Sheet 3 Patented Apr. 15, 1947 UNITED STATES PATENT OFFICE SEQUENCE RELAY Hazen C. Pratt, Detroit, Mich.

Application August 9, 1943, Serial No. 497,892

Claims. 1

This invention relates to relays and more particularly to lock-in sequence relays of the alternate make and break type.

A primary object of the invention is the provision of a simple, inexpensive, easily constructed and economically operated relay of the type in which the switch means is alternately latched in one condition of operation and unlatched for movement to another condition of operation upon successive energizations of the relay.

A further object is the provision of a relay of the type described above which is mechanically locked in the latched position and which has but few moving parts and is capable of long use without requiring adjustment or wearing appreciably.

A still further object is the provision of such a relay in which a rockable type of armature directly effects the closing and opening of the relay contacts and the rockable armature is mechanically locked in the latched position.

Another object is the provision of a mechanically latching and unlatching type of relay which avoids the use of cams, toggles, linkages, rollersv and other relatively complicated and expensive mechanisms which are subject to wear and require adjustment upon assembly and use of the relay.

Still another object is the provision of an alternately latching and unlatching type of relay in which a rockable armature constrained for movement between a pair of guide plates, a pair of operating springs and a pair of spring contacts constitute the only moving parts.

An additional object of the invention is to provide a sequence relay which can be manufactured in quantity at low cost, which will be reliable in its operation and durable in its wearing qualities, which will control relatively heavy currents with adequate pressure between the contacts and proper wiping action, and which will not require adjustments either in assembly or after being placed in service.

Still another object of the invention is to provide a sequence relay which, by its design, is particularly well adapted for incorporation into a transformer-relay combination whereby high voltage circuits can be controlled in one compact efficient unit by low voltage relay circuits.

Referring to the drawings, which illustrate a selected embodiment of the invention,

Fig. 1 is a plan view of the complete assembly, the relay being in the off (contacts left open) position;

Fig. 2 is a plan view with the top plate assembly and the armature removed;

Fig. 3 is the armature end view of the relay with the armature removed;

Fig. 4 is an end view of the armature assembly which consists of an armature main plate, two back plates and an insulating strip assembled together with rivets;

Fig. 5 is a top perspective view of the bottom plate of the relay;

Fig. 6 is a perspective view of the armature assembly showing that side which faces the core of the transformer-relay combination;

Fig. 6a is a top perspective view of the top plate of the relay;

Fig. 7 is a cross section of the complete assembly taken along the line l--l of Fig. 1, showing the armature released with the contacts left open;

Figs. 8, 9, and 10 are identical with Fig. 7, respectively showing the armature attracted, the armature released with the contacts left closed, and the armature again attracted;

Figs. 11, 12, 13, and 14 are cross sections of the complete assembly taken along the line 2-2 of Fig. 1, respectively showing the armature in the positions respectively shown in Figs. '7, 8, 9, and 10;

Figs. 15, 16, 17, and 18 are cross sections of the complete assembly taken along the line 3-3 of Fig. 1, respectively showing the armature in the positions respectively shown in Figs. 7, 8, 9, and 10; and

Fig. 19 is a schematic drawing showing the incorporation of the transformer-relay combination into a typical circuit.

In the selected embodiment the relay designated generally by numeral I0 is incorporated as an integral part of a transformer-relay combination. The transformer core H is of the closed loop type and has two transverse legs l2 and 13 upon which the primary coil I4 and the secondary coil l5 of the transformer are respectively wound, the primary coil l4 being on the leg l2 which is nearest the relay armature l6 where the flux path to the armature will be shortest, and the secondary coil l5 being on the other leg I3. Magnetic poles H are extensions of opposite sides of the transformer core II and longitudinally extending filler strips l8 of magnetic metal added above and below the core proper are provided to increase the face area of the magnetic poles.

The primary coil is normally constantly energized from a suitable source of alternating current drawing, like a bell ringing transformer, a minimum of current except during the momentary operation of the relay. The secondary coil 15 is normally open circuited and is connected to one or more normally open pushbuttons I 9 which are connected in parallel with each other. So long as the pushbuttons are open, only a small exciting current flows in theprimary coil I4, and substantially all of the magnetic flux of the core passes through the legs I2 and I3.v When any one of the pushbuttons I9 is depressed, the secondary coil I is short circuited and its induced current creates a back flux in the leg I3, increasing the reluctance of the path through leg I3. A substantial part of the flux from primary coil I4 shunting through magnetic poles [1, the air gap between the magnetic poles and the armature I6, and the armature I5, energizes the magnetic poles and attracts the armature.

The relay will operate as well as a simple sequence relay if the transformer assembly (two coils and core) is replaced by a single electromagnet (one coil and core) provided the magnetic pull on the armature is retained at the same in tensity. It will be obvious that, if the secondary coil and the secondary leg have both been omitted from the assembly, the remaining primary coil is connected in series with the pushbutton circuit and a source of power to operate as a simple electro-magnet, the pushbuttons, if more than one, remaining in parallel with each other. If, however, the source of power is at a high voltage and it is desired to operate the relay control circuit at low voltage, considerable economy can be realized by using the transformer-relay combination because in a separate transformer circuit a much larger transformer must be used than is used in the combination type relay.

Shading coils 23 of conducting metal extend about a portion of the iron making said magnetic poles I1 and cause the armature to remain in attracted position without any vibration or chattering as long as the circuit through the secondary coil remains closed.

The magnetic poles I1 are cut back at the top, see Figs. '7 to 18, in order to insure a much stronger magnetic pull at the bottom of the armature. The purpose of this will be described later. The cutting back of the magnetic poles also leaves room for the shading coils 20.

The core I I, with its magnetic poles I1, is laminated and comprises a plurality of magnetic metal stampings. The entire core unit, together with filler strips I8, and spacer strips 2I of suitable insulating material, is clamped and mounted between a top plat 22 and a bottom plate 23 by bolts 24 and nuts 25. The bolts 24 extend through a pair of mounting feet 26, the core stampings, the filler strips, the spacer members, and the top and bottom plates to clamp all of them into a rigid unitary structure.

The top plate 22 has a central transverse portion 21 which extends upwardly over the primary and secondary coils I4 and I5 and supports a pair of flexible springy contact strips 28 and 29. The top contact strip 29 overlies the bottom contact strip 29, as shown, and the strips are insulated from each other and from the plate portion 21 by strips 30 of insulating material. Rivets 3I rigidly clamp the strips 28 and 29 to the plate portion 2'1.

The top plate 22 is provided with a suitable opening for receiving the transformer windings I4 and i5 and at its forward end is provided with a latch lug slot 32 adapted to receive the forward ends of the contact strips 28 and 29. The strips 28 and 29 curve downwardly through the latch lug slot 32 and are provided with co-operating contacts 33 and 34. The contact strip 28 is provided with an elongated portion 35 which extends beyond the contact 33 and engages an insulating strip 38 upon the armature I6, as shown in Figs. 7 8, 9, and 10. The spring tension of the contact strip 28 is such that it constantly remains in contact with the insulating strip 36 and constantly provides a pressure or force on the armature tending to move it away from the magnetic poles IT.

The armature I6, which is adapted to be attracted towards the magnetic poles I'I upon energization of the relay and to move away from the magnetic poles upon de-energization of the relay, is mounted for sliding and rocking movement between the top and bottom plates 22 and 23 which serve as guides and stops for the armature in its various stages or sequences of operation, as will be hereinafter described. The armature, confined and limited in its travel by its lugs traveling in their slots, assumes successively two different positions when released from the magnetic attraction which draws it towards the poles. In one, Figs. 1, 7, 11, and 15, the contacts are left open and in the other, Figs. 9, 13, and 3.7, the contacts are left closed.

The armature l6 comprises an armature main plate 3'! and armature back plates 38. The armature main plate is provided with upwardly extending top stop lugs 39 and downwardly extending bottom stop lugs 40 adjacent opposite ends thereof. The top and bottom stop lugs are adapted to extend respectively through suitable tcp stop lug slots 4i in the top plate 22 and bottom stop lug slots 42 in the bottom plate 23 and support the armature I6 for sliding and a certain amount of pivotal movement. A latch lug 43 also extends upwardly from the top of the armature main plate 31 and is adapted to engage against the forward edge of the latch lug slot 32 to latch the relay in closed position, as illustrated in Fig. 9. The latch lug 43 is provided with latch lug shoulders 44 adapted to engage that part of the lower surface of top plate 22 adjacent the latch lug slot 32 to maintain the armature centered and to limit its upward movement, when the relay is in closed position. The armature main plate 37 is further provided with downwardly extending lock lugs 45 which engage lock lug slots 46 in bottom plate 23 to lock the armature main plate in its uppermost position when the relay is in its closed position so that latch lug 43 will remain engaged in latch lug slot 32.

A bent lug 41 extends downwardly from the armature main plate 31 through a bent lug slot 48 provided in bottom plate 23. A beveled face 49 on the rearward end of bent lug 41 is adapted to engage either on top of a short spring 50 or between the short spring 50 and a long spring 5|, both of which are attached to the bottom plate 23 with rivets 52. The bent lug 41, which successively rides up over, or forces itself down under, the short spring 50, depending upon whether the bent lug is inclined up, as in Fig. 7, or down, as in Fig. 9, selects which of the two positions the armature IE will assume upon release. Thus, in going from the o position (Fig. 7) to the on position (Fig. 9), the bent lug rides up over the short spring, as in Fig. 8. In going from the on position (Fig. 9) to the oil position (Fig. 7), on the other hand, the beveled face 49 of the bent lug strikes the end of the short spring and, by cam action, forces itself down under to the position shown in Fig. 10.

The long spring 5I, appearing in Figs. 7 to 10 inclusive, has the function of supporting the weight of the armature, particularly during its travel from the position illustrated at Figs. 8, 12, and 16 to that shown in Figs. 9, 13, and 17.

Without such a support, it may drop off the end of the short Spring too fast to be caught by the lock lugs. The relay will operate in any position and the long spring is necessary Only when the relay is operated in the horizontal position in which it is shown; it is not needed if the relay is operated in an upside down or any one of the various vertical positions.

When armature l6 rocks forward towards the magnetic poles -l1, in passing from the position illustrated in Fig. '7 to that shown in Fig. 8, the bent lug 41 presses down upon the short spring 50 which resists this pressure and tends to raise the armature vertically, initially holding the face of the latch lug 43 against the under side of the top plate 22. With the further forward motion of the armature, the latch lug clears the end of the latch lug slot 32 and the armature, raised by the spring pressure, will snap up to its upper extremity of travel as limited by the latch lug shoulders 44 bearing against the under side of the top plate at each side of the latch lug slot. Thereupon the latch lug takes its latching position in the latch lug slot, as shown in Fig. 8.

When the magnetic pull is released, in passing from the position illustrated in Fig. 8 to that shown in Fig. 9, the latch lug 43 engages in the latch lug slot 32. This catches and holds the top of the armature so that it cannot return to its original or Fig. 7 position, but assumes instead the position shown in Fig. 9. The bottom of the armature is not so held but is free to rock back under pressure from contact strips 33 and 34 to the position shown in Fig. 9. As the bottom of the armature rocks back, the beveled face of the bent lug clears the end of the short spring which is freed and allowed'to snap back to its original Fig. 7 position, as shown in Fig. 9. The armature is now in position for the start of the releasing cycle.

Upon the next movement of the armature towards the poles, passing from the position shown in Fig. 9 to that of Fig. 10, the bent lug 41, as it forces itself down under the short spring 50, draws the armature I6 down vertically to the position shown in Fig. 10, further downward motion being restrained by the lower face of the armature coming in contact with the upper surface of the bottom plate 23. This downward motion of the armature withdraws latch lug 43 from latch lug slot 32 (see Fig. 10). The armature is now unlatched, being held adjacent to the poles by the magnetic attraction only, this pull being resisted by the spring tension in the contact strips.

In the next operation, passing from the position illustrated in Fig. 10 to that shown in Fig. 7, the magnetic attraction is released, and the armature snaps back to its original position, as shown in Fig. '7, thus completing a cycle of closing and opening the contacts.

This explains the functioning of the latch and bent lugs whose performance should be fairly ob- ViOlls from the figures in the drawing once it is understood that the figures follow a definite cycle from the position illustrated in Fig. '7 through those shown in Figs. 8, 9, 10, and '7 successively, the magnetic attraction of the armature being alternately applied and released.

Figs. 11 to 14, inclusive, show the functioning of the lock lugs, and Figs. 15 to 18 the functioning of the bottom stop lugs in all four of the armature positions. The stop and lock lugs 39, 40, and 45, traveling in their respective slots 41, 42, and 46, confine and limit the travel of the armature to definite lines of travel and to definite stopping points as required for proper functioning of the relay.

The top stop lugs 39 confine the travel of the upper portion of the armature to a straight path up and back and limit its travel to the extreme positions shown in Figs. '7, 9, and 10, where the lugs come in contact with the ends of the slots 4|. In the Figs. 8, 9, and 10 positions the bottom stop lugs 40 limit the fore and aft travel of the bottom of the armature, the armature being at its high level, but in the Fig. 7 position the lock lugs 45, not the bottom stop lugs, limit the travel, the armature being at its lower level so that the lock lugs are low enough to encounter the ends of their slots. While inherent in the design, it is advantageous, particularly in the Fig. 7 position,

to restrict the outward travel of the armature as much as possible since the pull exerted by the magnetic poles becomes weaker as the gap becomes larger. In the forward position (Figs. 16 and 18) the top stop lugs 39, assisted by the bottom stop lugs 40, hold the armature off the poles. In conformity with good relay design practice, it is never considered advisable to let the armature ground on the poles, but it is particularly advisable in this relay where it is desirable to offer no obstruction to the vertically upward motion of the armature in passing from the position shown in Fig. 7 to that of Fig. 8 as the short spring 50 raises the armature to the latching position. If the armature grounds on the poles, an inordinately powerful magnetic attraction, always present when the air gap diminishes to or towards the vanishing point, will impede this upward travel of the armature and require a heavier short spring than would otherwise be necessary, thereby lessening the sensitivity and hence the usefulness of the relay.

The lock lugs are necessary to lock the armature in the on or Fig. 9 position and are just short enough to clear the ends of their slots 46 as the armature, released from the magnetic pull, rocks out at the bottom to the Fig. 9 position. In this maneuver, therefore, the lock lugs do not encounter the ends of their slots but pass a little way beyond, leaving their faces in position to be supported by the bottom plate 23. The extent of this movement outward is limited by the bottom stop lugs 40 as they encounter the ends of their slots 42 so that, in the Fig. 9 position, the armature comes to rest supported by the lock lugs at the bottom and is restrained from further outward movement by the latch lug 43 and the bottom stop lugs 40. Lacking such lugs, the relay would not be stable in this position but would, in response to any appreciable shock or jar, become unlatched and assume the Fig. 7 position because the pressure of the long spring 51 and the friction of parts is not sufficient to support the mass of the armature against any appreciable vibration. In addition, without such lugs the shock or vibration which occurs when the bottom of the armature snaps out to the Fig. 7 position will, at times, drop the armature out of the latching position, going direct from the Fig. 8 position to the Fig. 6 position, missing the on part of the cycle completely. The lock lugs effectively eliminate this possibility as they afford a firm support for the armature when it is in the Fig. 9 position, as should be evident from an inspection of Fig. 13.

It is essential to the operation of the relay that the armature, in advancing from the Fig. 7 to the Fig. 8 position, moves in towards the poles as fast or faster at the bottom as it does at the top. If the armature moves in top foremost, the bent lug slips in under the short spring instead of riding over it and the armature will advance to the Fig. 10 instead of the Fig. 8 position. If more than a little movement at the top of the armature is allowed before the bottom is fully home, the bent lug will slip ofi the end of the spring to pull in under instead of over it. This pulling in faster at the bottom is realized by making use of the fact that magnetic pull is much greater at small than at large air gaps and increases constantly as the gap is progressively shortened. In the Fig. '7 position the armature is inclined upward and outward from the magnetic poles ll so that the pull will be much greater at the bottom than at the top with the effect that the bottom of the armature will move in more rapidly, the top lagging behind until the bottom is fully advanced. As has been set forth above, the cut-back at the top of the magnetic poles i! also tends to insure a greater magnetic pull at the bottom of the armature. When the poles are not so cut back, the armature action may be somewhat erratic, the top coming in too fast at times so that the bent lug 4! may fail in its action. The armature I6 is cut down for the same purpose, as is apparent between the top stop lugs 39 and latch lug shoulders 44, Figs. 4 and 6.

The need for such a relay is particularly evident, for example, in connection with farmers yard lights, the farmer having occasion to turn his yard light, such as a yard light 53, Fig. 19, on or off from a number of different points, such as his house, his barn, or various outbuildings. The sequence relay is peculiarly adapted to this task since it advances, on successive current impulses, successively from the off to the on and back again to the off position so that it can be controlled by one simple relay circuit. Any number of pushbuttons are connected in parallel to give entirely independent control over the light from every pushbutton location. Using the transformer-relay combination, the control circuit may be operated at low voltage, materially reducing the cost of running the control lines. Compared with the three-way or the fourway switches and Wiring now used to give the farmer control over his light from two or more places, the transformer sequence relay has the advantage of lessened current consumption since the current the light draws does not have to travel out to and back from the switches with a resulting line loss. Sequence relays now on the market do not meet this need satisfactorily because they are all relatively expensive to manufacture, being constructed of a large number of parts including a sizeable proportion of screws, nuts, lathe turnings and formed stampings. They are not eihcient in operation, using, for the most part, a cam driven by a ratchet wheel or other complicated mechanisms for operating the contacts so that but little pressure can be applied to the contacts without requiring a relatively large pull on the armature. They frequently require adjustment on assembly and may require adjustment while in service because a relatively large number of parts is involved and each must be in correct relation to the others before the complicated mechanism, such as the pawl and ratchet wheel, will operate. They are not particularly well adapted for incorporation into the transformer-relay combination and any such combination, with existing sequence relays, would be bulky and relatively expensive to manufacture.

This relay compared with other sequence relays on the market, such as the cam and ratchet wheel type referred to above, requires but few parts, two springs, two contact strips, two insulating washers, two contacts, a top plate, a bottom plate, rivets, filler plates and an armature, which are all of relatively inexpensive manufacture being, for the most part, simple flat stampings with but one simple formed stamping, the bent lug. The relay has, other than the deflection of the four spring strips, but one moving part, that being the armature.

The space limitations, in this design, are not severe so the various lugs and springs can all be made of good size to be durable in their wearingqualities. The necessary clearances and limits are all incorporated in the design of the various stampings so no costly adjustments are required either on assembly or thereafter. Since the pressure on the contacts is direct, not through a lengthy and ineflicient system of mechanical linkages, without adversely affecting the sensitivity of the relay to control from distant points, a relatively heavy pressure can be used to control relatively heavy currents with moderate sized contacts. The large scale deflection of the two contact strips provides abundant wiping action so that the contacts will remain clean and serviceable. The relay adds very little to the size of the transformer proper, making a single compact unit available for installation in a relatively small space.

Changes may be made in the form, construction and arrangement of the parts without departing from the spirit of the invention or sacrificing any of its advantages, and the right is hereby reserved to make all such changes as fairly fall within the scope of the following claims.

The invention is hereby claimed as follows:

1. An electric sequence relay comprising the combination, with an electromagnet, including a coil adapted to be electrically energized for the operation of the relay, of an armature comprising a plate adapted to be moved bodily in one direction by said magnet when energized, yielding means operative at a. medial bearing portion of said plate to urge the same in the opposite direction, said plate being rockable about its medial portion with respect to said yielding means, support means operatively associated with cooperating portions of said plate on opposite sides of said medial portion for guiding and limiting the move- J ment of said plate, and switch means controlled by the so guided and limited movement of the plate.

2. An electric sequence relay comprising the combination, with an electromagnet, including a coil adapted to be electrically energized for the operation of the relay, of an armature comprising a plate adapted to be moved bodily in one direction by said magnet when energized, yielding means operative at a medial bearing portion of said plate to urge the same in the opposite direction, said plate being rockable about its medial portion with respect to said yielding means, support means operatively associated with cooperating portions of said plate on opposite sides of said medial portion for guiding and limiting the rocking and bodily movements of said plate, in a predetermined sequence, including yielding means operatively associated with said plate on one side of said bearing portion to yieldingly restrain rocking movement of the plate, and switch means controlled bythe'movement of said plate.

- 3. An electric sequence relay comprising the combination, with an electromagnet, including a coil adapted to be electrically energized for the operation of the relay, of an armature comprisport means operatively associated with cooperating portions of said plate on opposite sides of said medial portion, said cooperating portions and said support means forming cooperating stops for guiding and limiting the movement of said plate, yielding means operatively associated with said plate to urge it selectively to control the operation of said stops, and switch means controlled by the movement of said plate.

4. An electric sequence relay comprising the combination, with an electromagnet, including a coil adapted to be electrically energized for the operation of the relay, of an armature comprising a plate adapted to be moved bodily in one direction by said magnet when energized, yielding means operative at a medial bearing portion of said plate to urge the same in the opposite direction, said plate being rockable about its medial portion with respect to said yielding means, support means operatively associated with cooperating portions of said plate on opposite sides of said medial portion for guiding and limiting the rocking and bodily movements of said plate in a predetermined sequence, including spring means selectively engageable by said plate on one side of said bearing portion to yieldingly control the engagement of said stops, and switch means controlled by the movement of said plate.

5. An electric sequence relay comprising the combination, with an electromagnet, including a coil adapted to be electrically energized for the operation of the relay, of an armature comprising a plate adapted to be moved bodily in one direction by said magnet when energized, yielding means operative at a medial bearing portion of said plate to urge the same in the opposite direction, said plate being rockable about its media] portion with respect to said yielding means, support means operatively associated with cooperating portions of said plate on opposite sides of said medial portion for guiding and limiting the movement of said plate, said support means comprising spaced members formed with guide slots and I stop shoulders, said plate having cooperating portions extending in and movable along said slots in position to selectively engage said stop shoulders, and yielding means selectively engageable by said plate during sequential movement thereof in said guide slots for controlling the engagement of said cooperating portions with said stop shoulders, and switch means controlled by the movement of said plate.

6. An electric sequence relay comprising the combination, with an electromagnet, including a coil adapted to be electrically energized for the operation of the relay, of an armature comprising a plate adapted to be moved bodily in one direction by said magnet when energized, yielding means operative at a medial bearing portion of said plate to urge the same in the opposite direction, said plate being rockable about its medial portion with respect to said yielding means, support means operatively associated with cooperating portions of said plate on opposite sides of said medial portion, said cooperating portions and said support means forming cooperating stops for guiding and limiting the rocking and bodily movements of said plate in a predetermined sequence, a selector spring, said plate having a selector finger adapted to engage one side or other of said spring whereby to control the operation of said stops, and switch means controlled by the movement of said plate.

7. An electric sequence relay comprising the combination, with an electromagnet, including a coil adapted to be electrically energized for the operation of the relay, of an armature comprising a plate adapted to be moved bodily in one direction by said magnet when energized, yielding means operative at a medial bearing portion of said plate to urge the same in the opposite direction, said plate being rockable about its medial portion with respect to said yielding means, support means operatively associated with cooperating portions of said plate on opposite sides of said medial portion, said cooperatin portions and said support means forming cooperating stops for guiding and limiting the rocking and bodily movements of said plate in a predetermined sequence, a selector spring, said plate having a selector finger adapted to enga e one side or other of said spring, additional spring means acting on said plate to aid in determining the selective engagement of said finger with said selector spring whereby to control the operation of said stops, and switch means controlled by the movement 01' said plate.

8. An electric sequence relay comprising the combination, with an electromagnet having a pair of spaced poles and including a coil adapted to be electrically energized for the operation of the relay, of an armature comprising a plate having a medial bearing portion and pole facing zones on opposite sides of said medial portion, said plate being bodily movable in one direction by said magnet when energized, yieldin means operative at said medial portion of the plate to urge the same bodily in the opposite direction, said plate being rockable with respect to said yielding means about said medial portion, support means operatively associated with cooperating portions of said plate disposed on opposite sides of said medial portion for guiding and limiting the movement of said plate, and switch means controlled by the movement of said plate.

9. An electric sequence relay comprising the combination, with an electromagnet having a pair of spaced poles and including a coil adapted to be electrically energized for the operation of the relay, of an armature comprising a, plate having a medial bearing portion and pole facing zones on opposite sides or said medial portion, said plate being bodily movable in one direction by said magnet when energized, yielding means operative at said medial portion of the plate to urge the same bodily in the opposite direction, said plate being rockable with ,respect to said yielding means about said medial portion, support means operatively associated with cooperatin portions of said plate disposed on opposite sides of said medial portion for guiding and limiting the movement of said plate, and switch means controlled by the movement of said yielding means under the influence of said armature plate.

10. An electric sequence relay comprising the combination, with an electromagnet having a pair f spaced pole and including a coil adapted to be electrically energized for the operation of the relay, of an armature comprising a plate having a medial bearing portion and pole facin zones on opposite sides of said medial portion, said plate being bodily movable in one direction by said magnet when energized, yielding means operative at said medial portion of the plate to urge the same bodily in the opposite direction, said plate being rockable with respect to said yielding means about said medial portion, support means operatively associated with cooperating portions of said plate disposed on opposite sides of said medial portion for guiding and limiting the movement of said plate, and a switch controlled by the 12 movement of *saidplatasaid yielding means comprising the movable arm of said switch.

HAZEN C. PRA'I'I.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 10 Number Name Date 1,052,891 Corell Feb. 11, 1913 1,186,561 Evans June 13, 1916 1,980,458 Westerfelhaus. Nov. 13, 1934 775,145 Meyer Nov. 15, 1904 

